The invention relates to a limiting circuit breaker with high-speed contact opening control by Thomson effect, comprising, per pole, a movable assembly having a movable main contact bridge forming a main circuit with a pair of stationary main contacts connected to current terminals, a movable arcing contact bridge forming with a pair of stationary arcing contacts an arcing circuit connected in parallel to the main circuit, a movable assembly operating mechanism, for opening the main circuit and the arcing circuit, comprising a Thomson effect propelling part, a locking device of the movable assembly in the open position of the contacts and an unlocking control device, the main contact bridge being disposed between the stationary main contacts and the Thomson effect propelling part, the movable assembly comprising an operating rod securedly united to the main contact bridge, the Thomson effect propelling part comprising an annular opening coil surrounding said rod and an opening disk disposed facing the opening coil.
A circuit breaker of this kind is known from U.S. Pat. No. 3,302,144.
A limiting circuit breaker is moreover known (French Patent No. 2,377,087) wherein the Thomson effect operating mechanism is disposed in the bottom part of the switchgear unit, on the opposite side from the breaking chambers, between the current input conductors folded into a bracket. In this second type of device, the operating rod, securedly united to the opening disk of the propelling part, passes between the stationary contacts and repels the movable contact bridge to move it away from the stationary contacts. In the circuit breaker of the first type considered, however, the operating rod driven by the opening disk exerts a traction force on the movable contact bridge.
The object of the invention is to perfect a circuit breaker of the first type considered, so as to make its operation more reliable while at the same time achieving a compact structure at a minimum cost.